Nonsludging oil



Patented Feb. 2, 1937 UNITED STATES NONSLUDGING OIL Raphael Rosen,Cranford, N. J., assignor to Standard Oil Development Company, acorporation of Delaware No Drawing. Application December 30, 1933,

Serial No. 704,764

12 Claims.

The present invention relates to lubricating oils and to a process ofmaking the same and in particular to oils of low sludgingcharacteristics especially adapted to high temperature service.

The invention will be fully understood from the following description.

Sludge formation is particularly objectionable in oils used for hightemperature lubrication, for example, in the lubrication of automotiveengines. The causes of sludging are not clearly understood but itappears to bear some relation to the oxidation characteristics of theoil and to be aggravated by the presence of moisture. Sludge formationappears to be some form of polymerization or agglomeration of materialswhich have a low ratio of hydrogen to carbon and when these materialsreach a suiiicient degree of polymerization or agglomeration they becometotally insoluble in the lubricating oil from which they are produced.They thereupon separate and de- 2 posit on the valves, rings, grooves,underface of piston and in the crankcase of the engine. It'

has been noted that many highly refined oils show a high oxidation rateand while this is not clearly understood, it is believed that therefining treatment has removed oxidation inhibitors on the one'hand andin same manner eliminated the natural agents which have sludgedispersing powers.

It has been found that sludge formation can be reduced considerably bythe addition of certain dispersing agents. Just What action thesematerials have is obscure but it seems clear that the sludging tendencyof the oil can be greatly 35 reduced as measured either in actualoperation in the engine or by the Sligh numbers of the oils. Asindicated above, the action of these materials is obscure but it isbelieved that the action is perhaps two-fold, reducing the degree ofagglomeration or polymerization, and maintaining the materials whichhave agglomerated in a stable suspended form so that the deposition doesnot occur in the engine.

The substances having sludge dispersing prop-. 45 erties are hydrocarbonoils which are, in the first place, of the highest boiling range readilyobtainable, that is to say, they are markedly heavier than the oilsordinarily used for motor lubricants and should preferably besubstantially undistillable and'obtained as residuals. They shouldlikewise be of a strongly parafinic nature; that is to say, with a ratioof hydrogen to carbon corresponding as closely as possible to theparafiin series of hydrocarbons but they should be freeflowing liquids.Heavy cuts of naturally occurring oils, for example of bright stockscylinder oils or their extraction products and the like possess sludgedispersing powers to a noticeable degree but it is feeble at best andsuch large quantitles are required that these substances are im- 5practical, for example, to 30% or even as much as 50% are required togive a result comparable with that produced by as little as 1% of thesynthetic oils which will be disclosed below.

In a prior application,Serial No. 704,763, filed 10 December 20, 1933,by the present inventor, there is disclosed a similar composition ofmatter comprising on the one hand a wax-free oil; for example, an oilwhich has been dewaxed, with various sludge dispersers, some of whichare capable 15 of exerting pour inhibiting powers, if they had been usedin the presence of a wax-containing oil.

The present case clearly distinguishes from the above application inthat it relates exclusively to compositions of waxy or wax-containingoils with 20 sludge dispersers of the type which are incapable ofsubstantially reducing pour point. I

The sludge dispersers which are used inthe present invention areproduced synthetically and the physical characteristics are quitesimilar to the heavy naturally occurring paraflinic resid-i uals exceptthat the dispersers are of higher molecular -weight and. higher boilingpoint. Among the condensationproducts those produced from oily liquidlubricating fractions of paraffin or mixed base crudes may be used.Condensation is accomplished by first rendering them unsaturated eitherby cracking or by other equivalent means, for example chlorination anddechlorination, and this first step is followed by condensation by meansof aluminum chloride or other known catalysts of the same type. Crackedwaxes may-be so condensed and these various unsaturated'materials may becondensed either alone or with aromatic hydrocarbons such as benzol ornaphthalene, which serve as a condensation nucleus. It is understood,however, that the amount of the aromatic material is sufiiciently smallso that the character of the condensation .product is substantially thatof a saturated hydrocarbon, as shown by its high ratio of hydrogen tocarbon.

Chlorinated oils may be condensed in the same manner as indicated above,either alone or in the presence of an aromatic hydrocarbon. Chlorinatedwaxes may, of course, be condensed alone or with aromatics such asnaphthalene or benzol, but these give rise to pour inhibitors, ifcondensation is conducted at low temperatures, say below 150 orpreferably 125 F., and such materials do not fall within the scope ofthe present invention, but on the other hand, if the condensationtemperature is raised to 200 or 250 C., the product has substantially nopour inhibiting properties and is contemplated for use in the presentcompositions. Also, by increasing the proportion of aromatics toparafdnic derivative, non-pour inhibitors can be produced even bycondensation at low temperatures. Condensation of liquid hydrocarbonsconducted by electrical means, that is by the action of high frequencyelectric discharges, may be used also for the present purposes, namely,as sludge dispersing agents, but the analogous condensation products ofwax are not contemplated since those materials show definite pourinhibiting characteristics.

In making the various materials outlined above it is preferable toselect the heaviest naturally occurring oils or waxes, and it is foundthat petrolatum, for example, is more suitable as a starting materialthan parafiin wax. The condensation products are more effective than thenaurally occurring oils and are ordinarily useful in proportions of 1 to2%, and they should not be used in very much larger quantities than mentioned above because for some unknown reason, if the quantity is toogreat, the sludge dispersing power is lost. It is always preferable touse less than 5% of the material. In such quantities the condensationproducts do not appreciably afiect the other properties of the motoroils to which they are added, for example, when used in the optimumquantities viscosity need not be raised more than 2 to 5 seconds Sayboltat 210 F.

The sludge dispersing agents which have been disclosed above areparticularly desirable when used in combination with inhibitors foroxidation. These latter materials are well known in the art but it hasbeen found that they almost invariably increase the Sligh number of theoil to which they are added. This defect is entirely corrected when asludge disperser is added in combination with the oxidation inhibitor soas to produce a stable oil of low Sligh number and low sludgingcharacteristics. .Any of the known oxidation inhibitors may'be used andamong these are mentioned the phenolic compounds, especially thecresols, diand tri-hydroxy phenols and cresols, resorcinol, hydroquinoneand pyrogallol. The naphthols, such as alpha naphthol and beta naphtholor their alkylated derivatives, are also used; likewise the aromaticdisulphides and mercaptans are satisfactory, as well as the aromatic oraliphatic polysulphides, particularly the trisulphides which are notcorrosive. Inhibitors containing hydroxyl, amino, disulphide andpolysulphide groups attached to an aromatic nucleus to which is alsoattached stabilizer groups such as oxygen or sulphur as an ether areparticularly desirable. These materials are merely mentioned as examplesof a very large or well-known class. Any of these may be used in thepresent compositions in conjunction with sludge dispersers of the classmentioned above.

As has been indicated above, the lubricating oils used in the presentcompositions are those containing wax, so as to have relatively highpour points. On the other hand, the sludge disperss agents are thosecondensation products which do not possess in themselves a power ofreducing the pour points. It should be underood, however, that inaddition to the sludge dispersing agents pour inhibiting substances maybe added, for example of the type disclosed in U. S: 1,815,022, or thoseprepared by the condensation of chlorinated and subsequentlydechlorinated hydrocarbon waxes or the condensation products produced bythe electrical treatment of hydrocarbon waxes. Other pour inhibitorssuch as zinc, magnesium and aluminum, and other metallic salts of thegroup of acids produced by the air oxidation of paraffin wax, may alsoserve, but it is of course preferred to use hydocarbon productsthroughout.

The following examples of oils made in accordance with the presentinvention will illustrate the composition and the action of thematerials.

Example I To a motor oil S. A. E. 20 ,with a Saybolt viscosity of 58seconds at 210 F. is added as a sludge inhibitor 1% of a material madeby blending parts chlorinated petrolatum with 30 parts of naphthalene atrelatively high temperature, so as to obtain a thick oily condensatewithout any substantial pour inhibiting properties. oil showed a Slighnumber (24 hours) or 30.5, sec Proc. Am. Soc. for Treating Materials24,964, 11 (1924). The Sligh value of the blend containing the disperserwas 18.9. There was no change in the pour point within the accuracy ofthe determination.

Ezrample II To the same base oil used in Example I is added 5% of adisperser made from polymerized fractions of cracked wax. The blendedoil showed a 24 hour Sligh of 14.2. The particular material added wasnot a pour inhibitor.

Example III To an oil of the composition shown in Example II is added asan oxidation inhibitor .1% of alpha naphthol.

Example IV To a 20 S. A. E. motor oil is added 1% of a heavy oilproduced by condensing a vapor phase naphtha with 30% of benzol. Thecondensation was accomplished with aluminum chloride. The original pourpoint was unaffected and the original Sligh (24 hours) was reduced from30.5 to about 1.0.

While the present invention is mainly directed to oils for automotiveengine lubrication, it is to be understood that it is not limitedentirely to this field, since the invention is useful in various otherfields, for example, in turbine oils as well as cable or otherinsulating compounds.

The present invention is not to be limited by any theory of the actionof sludge dispersers or of oxidation inhibitors, nor to any particularmembers of either of those classes of substances, but only to thefollowing claims in which it is desired to claim all novelty inherent inthe invention.

I claim:

1. An improved lubricating oil of reduced sludging tendencies whichcomprises a wax containing mineral lubricating oil and a small quantityof a dispersion agent prepared by condensation of high boilinghydrocarbons at such elevated temperatures as to produce condensateswithout pour inhibiting properties.

2. Composition according to claim 1 in which the condensation isefiected by means of aluminum chloride and at temperatures above 200 C.

The original 3. Composition according to claim 1 in which high boilingolefin hydrocarbons are condensed in the presence of aluminum chlorideand at temperatures above 200 C.

4. Composition according to claim 1 in which high boiling olefins arecondensed with aromatic hydrocarbons in the presence of aluminumchloride and at temperatures above 200 C.

5. Composition according to claim 1 in which chlorinated paraffinichydrocarbons are condensed in the presence of aluminum chloride attemperatures above 200 C.

6. Composition according to claim 1 in which chlorinated paraffinichydrocarbons are condensed with aromatics in the presence of aluminumchloride at temperatures above 200 C.

7. An improved lubricating oil of reduced sludging tendencies whichcomprises a wax containing mineral lubricating oil and a small quantityof a dispersion agent prepared by condensing chlorinated petrolatum withnaphthalene at a temperature above 200 C., said agent when prepared atsuch temperature not having pour inhibiting properties.

8. Composition according to claim 7 in which less than 5% of thedispersion agent is added to the oil.

9. Composition according to claim 7 in which between 1 and 2% of thedispersion agent is added to the oil.

10. An. improved lubricating oil of reduced sludging tendencies, whichcomprises a wax-containing petroleum lubricating oil containing insolution a small quantity of a dispersion agent comprising a synthetichydrocarbon prepared by condensing high-boiling olefin hydrocarbons,obtained by dehydrogenating a fraction of a paraffinic and mixed basepetroleum, at such elevated temperature as to produce a condensatewithout pour inhibiting properties.

11. A composition according to claim 1, in which said dispersion agentis prepared by condensing high boiling olefin hydrocarbon with cyclichydrocarbons at such elevated temperature as to produce condensateswithout pour inhibiting properties.

12. A composition according to claim 7 in which said dispersion agent isprepared by condensing chlorinated petrolatum with about 30% ofnaphthalene at a temperature above 200 C., said agent when prepared atsuch temperature not having pour inhibiting properties.

RAPHAEL ROSEN.

